Spring structure for sewing machines and the like



Dec" 1 1925. l,564,1 74

T. J. HAYES SPRING STRUCTURE FOR SEWING MACHINES AND THE LIKE Filed April 27. 1923 Patented Dec. 1, 1925.

UNITED STATES PATENT OFFICE."

THOMAS J. HAYES, OF EAST ST. LOUIS, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO LEWIS INVISIBLE STITCH MACHINE CO., A CORPORATION OF MAINE.

SPRING STRUCTURE FOR SEWING MACHINES AND THE LIKE.

Application filed April 27, 1923. Serial No. 635,006.

To all whom it may concern:

Be it known that I, THOMAS J. HAYES,

a citizen of the United States, residing at East St. Louis, in the county of St. Clair and State of Illinois, have invented certain new and useful Improvements in Spring Structures for Sewing Machines and the like, of which the following is a specification.

It is a generally-recognized fact of mechanics that it is extremely difficult to provide and mount a working spring,and particularly a wire spring having a bodycoil and a vibratable extension or working 1 legso that it will not crystalize and break when subjected to constant and rapid flexing in the operation of a high-speed machine. A salient object of my invention is to provide a spring construction of the charactor above referred to which will have long life under the stated conditions, will be very free and snappy in action, and yet will be adequately and firmly supported and guided for directing of its activity, and which nevertheless will be simple, inexpensive, and easily adjustable as to tension. Other and further objects of my invention will become apparent from the following description taken in conjunction with the accompanying drawings, and for the attainment of these objects my invention consists in the features of construction and combinations of parts hereinafter set forth and claimed.

In the drawings wherein I have illustrated my invention as applied in the return-spring fora feed-part of a high-speed sewing machine, and as being of a particular construction especially adapted to that situation and work (but without intent to limit my invention in its broader aspects to such specificembodiment), Fig. 1 is a side elevation of a sewing machine feed mechanism embodying my improved spring structure; Fig. 2 is a vertical section on line 22 of Fig. 1; Fig. 3is a detailof the spring structure, yiewed from the left ofFig. 2, and Fig. 4 is a section on line 44 of Fig. V

In the drawings, the spring structur 10 is shown as the return-spring for a feeddog 11 of a sewing machine mechanism, such spring structure being constructed and arranged for action both to raise the dog vertically and to, impel it longitudinally toward the right in Fig. 1, so as normally to position said dog in raised, retracted station. The particular feed mechanism illustrated in Fig. 1 is fully shown and de scribed in my copending application Serial No. 474,031, filed May 31, 1921, and a brief description will suflice to make understandable the particular application of the spring structure 10. In the sewing machine head 12 there are disposed the needle bar 13 and the presser bar 14 of well known construction, said presser bar having attached thereto a feed-frame 15 terminating at its bottom in a presser foot 16 through which the feed-dog 11 works in acting upon material supported by the work plate 17, such feeddog, in some installations, coacting with a primary feed-dog l8 suitably operated from below the Work plate 17 and working through openings in the latter. An actuator 19 is suitably connected at its free end, as at 20, to the needle bar 13 to be vertically reciprocated thereby, such actuator being pivotally supported as at 21 in the frame 15 and, through suitable cammechanism 22 (not necessary here to describe in detail), actuating a depressor-lever 23, which coacts with an upper surface of the feed-dog 11 to depress the latter, and also actuating a feed-lever 24c to the lower extremity of which the feed-clog 11 is pivoted as at 25, so that the feed-dogwill be positively advanced by such lever. At a suitable time in the excursion of the needle bar 18, while the needle is out of the work, the respective levers 23 and 24 90 controlled by the actuator 19 will force the feed-dog down from its normal position into worloengagement and also will impel it positively in a feeding direction (leftward in Fig. 1), and thereafter, as these positively-actuated levers free the feed-dog for retraction, the spring structure 10 must both elevate and retract the dog to its initial position. Remembering that such sewing machines may be operated at very high 100 speed, calling for several thousand feeding operations per minute, it will be understood that the spring mechanism 10 is subjected to very severe conditions, and that its activity, its certainty and precision in opera- 105 tion, and its longevity are of greatest importance to the success of the feed mechanism. o.

The spring-element 30, in the form shown, is fashioned of wire, suitably tempered, and 110 ill) is of the type providing a body-coil and a working-extension comprising, in part at least, a tangential continuation of the last turn of the coil. For the particular working requirements above referred to, in the stated mechanism the spring element has two multiple-turn coils, to-wit, the butt-coil 31 and the middlecoil 32, these being connected by the working leg 33 which is preferably generally vertically arranged and forms a tangential extension of and union between the last loop of the butt-coil and the first loop of the middle-coil, while the middle coil 32 has a working leg or extension 34, preferably approximately tangential to its last coil and extending in a horizontal direction approximately at right angles to the working leg 33. It will be apparent that with the working extremity 85 of leg 3% looped about an 'httachu 3' pin 36, or otherwise suitably connected to the feed dog 11, and the butt-coil 31 suitably connected at its first turn to the frame 15 of the presser foot feed structure, both the lifting motion and retracting motion above referred to will be imparted to the feed dog, the horizontal working leg and the middle coil 32 being principally active in imparting upward motion to the feed-dog, and the generally vertical working leg and butt-coil 31 being principally active in imparting horizontal retraction-movement to such dog.

For attaching, guiding and djusting the tension of the spring element 301 provide a spring-holderand-guide 41:0 which acts also as a tension-adjusting device, this spring-holder coacting with the butt-coil of the spring element 3 The springholding structure comprises a barrel or cup ll and a clamping member or screw l2 about the axis of which the cup-member is rotarily adjustable but which clamps the cup-member to the frame piece 15 in any position of adjustment of the cup. The stated cup member has a cylindrical body or barrel 43 of such internal dimensions that it neatly and snugly receives the butt-coil 31 when the latter is not under tension, so that the cylinder wall may normally give to the multiplicity of turns of the coil an even, complete support that will very effectually hold the spring against unintentional displacement and will properly position, and direct the activities of, the working extension of the butt-coil which extends beyond the cup. At one end the cup has a head 44 against which the first turn of the coil abuts, this head being preferably outwardly extended to form a knurled flange d5 for convenient finger-operation in adjusting the spring tension, and through this head the screw 42 extends in a position coaxial with but well separated at all points from the butt-coil 31. The cylinder wall 43 is slotted as at 46 from the open end of the cylinder to the head 44:, as a convenient way of holding the butt-coil, such slot being of suitable width neatly to receive a tailprojection 31 from the first turn of coil 31. The open end of the barrel is also shallowly recessed through quite a wide arc, as at 47, to leave a free opening for the working leg'33 of the spring element, and for permitting the cup to be turned through quite a wide angle of rotative movement, for adjustment of the spring tension, without interfering with the freedom of the working leg 33.

it will be seen that with the parts assembled as shown in the drawings, screw 42 may be loosened and the cup turned, by means of its knurled flange d5, to change the position of the anchorage-tail 31' of the buttcoil with respect to the position of the active end of the spring, thereby to vary the spring tension; and the screw 42 may be tightened again to clamp the cup in adjusted position, the flat contacts between the underside of the screw head and the end of the cup, and between the open face of the cup and the plate 15, giving a very secure bearing that does not facilitate accidental loss of adjustment. Thus it will be observed that the spring is very accurately guided and thoroughly supported, and yet has greatest freedom of action. The cam-impelled movements of the feed dog 11, which increase the tension on the spring, tend to contract the butt-coil 31 and this coil, because of its wide spacing from the screw 42, is perfectlyfree to respond to this contraction effort, whereas were the spring coil supported on the screw 42 (as is ordinarily the case in the mounting of springs of the general character described) the attempted contraction of the spring would be resisted and undue strain would be thrown upon the last turn of the butt-coil, tending to make it crystallize and break close to the juncture of the end turn with the tangential extension 33. It will further be understood, that the contractile efforts aforesaid affecting the butt-coil 31 is tiny in linear extent in proportion to the length of the coil, so that in the operation of the device the coil-contraction is very slight indeed and effective support and guidance of the coil is not lost, nor is the coil caused to wabble or tend materially to displace itself in its cup. I have found in experience that a spring positioned and mounted as above described has a length of life and a continuing snappiness of action far exceeding springs mounted in hithertoknown fashion for the same work.

It will be understood that while I have described in considerable detail a particular embodiment of my invention, for purposes of full disclosure, changes in detail of construction and arrangement may be made without departure from the spirit of my invention within the scope of the appended claims.

I claim:

1. The combination with a suitable support and a working part of a high speed machine, of a spring structure for moving said working part comprising a wire spring having a butt-coil adapted to be contracted and a working extension therefrom that is connected to said working part, a barrel engaging the exterior only of said butt-coil and snugly investing said coil, and means for securing said barrel to said support.

2. The combination of a wire spring having a butt-coil and a working arm forming an extension from the last turn of said coil, and a spring-holding structure comprising a support extending within the coil and spaced therefrom, a barrel exteriorly fitting neatly over the spring-coil and secured upon said support, said spring-coil having its first turn secured to said holding structure.

3. A spring-structure comprising a cylindrical butt-coil and a working extension from the last turn of said coil adapted, when working, to tend to contract the coil; a cylindrical cup member to which the first turn of the coil is connected, said cup member snugly investing the cylindrical coil and affording also end bearing for the first turn thereof, a support against which said cup member may be clamped, and a clamping screw for positioning said cup member on said support extending through said cup member but spaced from the interior of the cylindrical spring coil.

4. A structure as set forth in claim 2 wherein the first turn of said spring coil has an outwardly-bent tail and said barrel has a slot in its side wall to receive said tail for securing the butt-coil thereto, said barrel being rotatably adjustable on the support to adjust with it the coil.

5. A structure as set forth in claim 3, wherein said spring-receptive cup is adjustable rotatably with respect to the clamping screw and has at its open end a circumferentially-elongate ;l recess to receive the working extension of the spring coil and permit rotative adjustment of the cup on said supporting screw without interfering with the working extension of the spring.

6. A spring-assembly for cooperation with a support and a working part, comprising a wire spring having a cylindrical coil of a multiplicity of turns with a tail extension from its first turn and a working extension from its last turn, a spring-receiving cup having an opening to receive the spring tail and having a side-wall recess, circumferentially elongated, to receive the working extension, the side walls of said cup snugly engaging the spring coil and the closed end of said cup engaging, flat-wise, the end turn of said spring, and a clamp screw, for engagement with the said support, extending through the head of the cup and spaced from the interior of the spring-coil.

THOMAS J. HAYES. 

